Ask HN: How to contact a writer of a book without LinkedIn/Twitter?

Hello, I was just trying to message an author of this [0] book to get a discount( due to currency rates -1$=6.85 my currenxy- so %50 is fine with me)

He does not respond on Linkedin. Also his twitter cannot be reached from his site. What to do? Btw, I finished first 200 pages (of 400 pages free preview) and loved it. Thank you in advance.

[0]https://alvinalexander.com/scala/learning-functional-programming-in-scala-book